Parse ELMAH logs via LINQPad.

Elmah Log Parsing.linq

<Query Kind="Program" />

void Main()
{
	// If false, will disable all debugging messages.
	var debug = true;
	// If true, files will not really be deleted.
	var testingDeletions = false;
	// If true, dump the file name of Elmah logs that are deleted.
	var debugDumpDeletedFileName = true;
	// If true, error messages will be dumped to the display, if the file isn't deleted.
	var debugDumpErrorMessage = true;
	
	var deleteFile = false;

	var directoryPath = @"\path\to\App_Data\Elmah.Errors";
	
	var directory = new DirectoryInfo(directoryPath);
	var directoryFiles = directory.GetFiles("*.xml");
	
	string.Format("Total errors: {0}", directoryFiles.Count()).Dump();
	
	var files = directoryFiles.OrderByDescending(f => f.CreationTime).Take(1000); // 19984
	
	string.Format("Errors parsing: {0}", files.Count()).Dump();
	
	foreach (var file in files)
	{
		try {
			var xmlFile = new ElmahXmlFile(file.FullName);
			deleteFile = false;
			/* Add custom logic to trigger deletions here. */
			if (
				(xmlFile.Details.Contains("submitApp_Click") && xmlFile.Message == "Thread was being aborted.")
				|| (xmlFile.Message == "User came from beta")
			) {
				deleteFile = true;
			}
			/* End custom logic to trigger deletions */
			// Delete the file, if not testing.
			if (deleteFile) {
				if (debug && debugDumpDeletedFileName) {
					string.Format("Deleting file: {0}", file.Name).Dump();
				}
				if (!testingDeletions) {
					file.Delete();
				}
				continue;
			}
			
			if (debug) {
				if (debugDumpErrorMessage) {
					string.Format("Message: {0}", xmlFile.Message).Dump();
				}
			}
		}
		catch (XmlException ex) {
			ex.Message.Dump();
			file.Name.Dump();
		}
		catch (Exception ex) {
			ex.Message.Dump();
		}
	}
}

// Define other methods and classes here
public class ElmahXmlFile {
	public string Message;
	public string Details;
	public string PageUrl;
	public string QueryString;

	public ElmahXmlFile(string xmlUri) {
		var xml = XDocument.Load(xmlUri).Root;
		if (xml.Element("serverVariables") != null && xml.Element("serverVariables").Elements("item").Where(i => i.Attribute("name").Value == "PATH_INFO").Count() == 1)
		{
			this.PageUrl = xml.Element("serverVariables").Elements("item").First(i => i.Attribute("name").Value == "PATH_INFO").Element("value").Attribute("string").Value;
		}
		if (xml.Element("serverVariables") != null && xml.Element("serverVariables").Elements("item").Where(i => i.Attribute("name").Value == "QUERY_STRING").Count() == 1) {
			this.QueryString = xml.Element("serverVariables").Elements("item").First(i => i.Attribute("name").Value == "QUERY_STRING").Element("value").Attribute("string").Value;
		}
		
		this.Message = xml.Attribute("message").Value;
		this.Details = xml.Attribute("detail").Value;
	}
}